1. Field of the Invention
The present invention relates to a pixel and a light emitting display including the pixel, and more particularly, to a pixel circuit and a light emitting display in which an image is displayed with desired brightness.
2. Discussion of Related Art
Various flat panel displays have recently been developed as alternatives to a relatively heavy and bulky cathode ray tube (CRT) display. The flat panel display includes a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), a light emitting display (OLED), and similar devices.
Among the flat panel displays, the light emitting display can emit light for itself by electron-hole recombination. Such a light emitting display has advantages in that response time is relatively fast and power consumption is relatively low. Generally, the light emitting display employs a transistor provided in each pixel for supplying current corresponding to a data signal to a light emitting device, thereby allowing the light emitting device to emit light.
FIG. 1 illustrates a conventional light emitting display. A conventional light emitting display includes a pixel portion 30 including a plurality of pixels 40 formed in a region defined by intersection of scan lines S1 through Sn and data lines D1 through Dm; a scan driver 10 to drive the scan lines S1 through Sn; a data driver 20 to drive the data lines D1 through Dm; and a timing controller 50 to control the scan driver 10 and the data driver 20.
The timing controller 50 generates a data control signal DCS and a scan control signal SCS corresponding to an external synchronization signal. The data control signal DCS and the scan control signal SCS are supplied from the timing controller 50 to the data driver 20 and the scan driver 10, respectively. Further, the timing controller 50 supplies external data to the data driver 20.
The scan driver 10 receives the scan control signal SCS from the timing controller 50. The scan driver 10 generates scan signals on the basis of the scan control signal SCS and supplies the scan signals to the scan lines S1 through Sn.
The data driver 20 receives the data control signal DCS from the timing controller 50. The data driver 20 generates data signals on the basis of the data control signal DCS and supplies the data signals to the data lines D1 through Dm while synchronizing with the scan signals.
The display portion 30 receives first voltage ELVDD and second voltage ELVSS from an external power source, and supplies them to the respective pixels 40. When the first voltage ELVDD and the second voltage ELVSS are applied to the pixels 40, each pixel 40 controls a current corresponding to the data signal to flow from a first power line supplying the first voltage ELVDD to a second power line supplying the second voltage ELVSS via the light emitting device, thereby emitting light corresponding to the data signal.
That is, in the conventional light emitting display, each pixel 40 emits light with a predetermined constant brightness corresponding to the data signal, but cannot emit light with desired brightness because transistors provided in the respective pixels 40 are different in threshold voltage from one another. Further, in the conventional light emitting display, there is no method of measuring and controlling a real current flowing in each pixel 40 corresponding to the data signal.